Singer announced the casting on his Twitter by thanking director Brett Ratner for letting the characters played by the three actors to be kept alive so they can make a return. "Very excited to welcome #annapaquin, @ellenpage & @shawnrashmore to #XMen #DaysofFuturePast - thank you @BrettRatner for letting them live!" so he wrote.

Paquin and Ashmore have all appeared in three "X-Men" movies, while Page didn't join the franchise until 2006's "X-Men: The Last Stand" which was directed by Rattner. Joining them to join the "X-Men" crew in the upcoming movie are the likes of Hugh Jackman as Wolverine, Patrick Stewart as Professor X and Ian McKellen as Magneto.

Based on the comic book storyline, "Days of Future Past" which ran in Uncanny X-Men #141 and 142 back in 1981 during Chris Claremont and John Byrne's run introduced the idea of an alternate future for Marvel's mutants that grew out of the Brotherhood of Evil Mutants killing an important senator, leading to a future where all mutants are hunted by Sentinels.